Author Question: When is a planetary body or a star used as a slingshot and why? (Read 1478 times)

Hawke · **on:** Jun 23, 2013

Of course it involves the use of forces and which are those forces and more important what is the maximum velocity the projectile shot out of the sling can achieve keeping in view the present technology and further more could it leave the solar system and be able to reach another star during the lifetime of a person riding the projectile - say a space ship?

curlz · **Reply #1 on:** Jun 23, 2013

It all has to deal with Howard Stern don't you know.

coco · **Reply #2 on:** Jun 23, 2013

A space craft would use the gravitational force of a large body to increase its velocity and/or change direction. The speed achieved would depend in part on the strength of that gravitational field. The nearest star to our sun is about 4 light-years away which means it takes light 4 years to cover that distance (about 23 trillion miles). Using the most advanced technology we have today, a space craft would only be able to achieve about 10-20% of light-speed so it would take about 20 to 40 years to reach the nearest star at top speed. However, because of the mass of the fuel and food and water needed to supply the astronaut on such a mission and the time needed for acceleration and braking, it becomes nearly impossible with current technology to reach it in a human lifetime.

j_sun · **Reply #3 on:** Jun 23, 2013

It depends on the mass of the object used to slingshot it and the mass of the object to be propelled. It would also depend on the objects entrance velocity and orbital trajectory......As EBK said...even with the help of an ion drive to keep our speed accelerating it would take 80 years to get to Alpha Centauri....

Melanie · **Reply #4 on:** Jun 23, 2013

the force is gravity. a space vehicle may use the gravity of another body to gain speed to shorten its time to its destination. the speed attained depends on the mass of both. as the vehicle rounds the body, it is propelled at the greater speed in the opposite direction.

Millan · **Reply #5 on:** Jun 23, 2013

Quite a few of our spacecraft have used the slingshot effect to save on fuel. Didn't the Cassini mission do more than one slingshot around Venus and Earth? (My memory might be a little rusty here.)

The really neat thing is that you can steal a little energy from a planet as you whip around it and give your spacecraft a big boost with no need for any fuel! It's a great trick.

Millan · **Reply #6 on:** Jun 23, 2013

It's also called a gravity assist. When you launch you need all the help you can get. If you orbit the earth or any other body and go with its speed, especially around the equator, then when you break orbit it's almost like the planetary body adds it's speed to your effort.

Sandstorm · **Reply #7 on:** Jun 23, 2013

The boost of a spacecraft using a gravity assist depends largely on the orbital velocity of the planet and the angle the trajectory is bent. However, the orbital velocity is the limiting factor; IIRC, a spacecraft can't get more than a 2x planetary velocity boost. That is, if a planet is going around the Sun at 13 km/s, it is physically impossible for the spacecraft to get a heliocentric boost greater than 26 km/s.

Furthermore, the faster the spacecraft enters the gravity well, the less effective the gravity assist is, because the trajectory is "bent" less. For a spacecraft travelling a significant fraction of light-speed, a gravity assist would provide no significant benefit.